Durene-rhodium(I) complexes. Crystal structures of the complexes [Rh(durene)(diolefin)]ClO4 (diolefin  tetrafluorobenzobarrelene or trimethyltetrafluorobenzobarrelene)

The crystal structures of [Rh(durene)(diolefin)ClO₄ (diolefin  tetrafluorobenzobarrelene (TFB) and trimethyltetrafluorobenzobarrelene (Me₃TFB)) have been solved by standard X-ray single crystal methods. The compounds crystallize in the space groups R₃c for the unmethylated TFB compound and P2₁/n for the methylated one. The cell dimensions are 25.7586(5), 17.0059(4) Å and 12.6686(6), 11.5565(3), 16.7269(8) Å, β  104.023(5)°, respectively. The refinement was taken to R values of 0.04 and 0.06, respectively. The arene in the TFB derivative has a distorted inverted boat conformation which becomes a skew one in the Me₃TFB compound. These puckering seems to be related to the tendency of rhodium(I) to achieve square-planar coordination.     

Cationic di- and mono-carbonyl complexes of manganese(I)

The complexes fac-O₃ClOMn(CO)₃(NN) (NN = 1,10-phenantroline (phen) or 2,2'bipyridine (bipy)) react with an excess of the ligands L [L = P(OR)₃ or P(OR)₂Ph, R = Me or Et] in refluxing ethanol to give cis-trans-[Mn(CO)₂-(NN)L₂]ClO₄, or the more highly substituted [Mn(CO)(NN)L₃]ClO₄ if the reaction is carried out under UV irradiation. Carbonylation at normal pressure of the latter complexes results in the formation of cis-cis-[Mn(CO)₂(NN)L₂]ClO₄, which undergo isomerization to the cis-trans isomer when heated in acetone.Treatment of fac-O₃ClOMn(CO)₃(dpe) (dpe = 1,2-bis(diphenylphosphino)-ethane] with bipy or phen in refluxing ethanol gives the corresponding cis-[Mn(CO)₂(NN)(dpe)]ClO₄ complexes, and irradiation of these with UV in the presence of an excess of P(OR)₃ (R = Ph, Et or Me) gives the monocarbonyls [Mn(CO)(NN)(dpe)L]ClO₄.     

Oxythallation of norbornene derivatives with thallium(III) acetate in methanol

Treatment of norbornene, norbornadiene, benzonorbornadiene, and chloro- and methoxy-benzonorbornadiene with thallium(III) acetate in methanol affords only the corresponding cis-exo-acetoxythallation adducts in a sharp contrast to oxymercuration of such strained olefins where methoxymercuration prevails. In the cases of substituted benzonorbornadienes the products are obtained as the regioisomeric mixtures, the isomer ratio being determined by ¹³C NMR. In the cases of 5-norbornene-2,3-dicarboxylic anhydride, 5-norbornene-2-methyl-2,3-dicarboxylic anhydride, and 5-norbornen-2-endo-carboxylic acid, lactonization occurs to give a trans-oxythallation adduct having a lactone ring, no introduction of either methoxy or acetoxy groups being observed. ¹H and/or ¹³C NMR data for several new oxythallation adducts are provided. The alkaline sodium borohydride reduction of adducts in methanol affords mainly the parent olefin together with 10–16% yields of the corresponding exo-alcohol.     

Cleavage by halogens of carbon—cobalt bonds in organometallic complexes of cobalt(III) : III. Kinetics and mechanism of the reactions of organobis(dimethylglyoximato)cobalt(III) complexes with iodine in chloroform

The kinetics of the reaction between organocobaloximes, RCo(DH)₂H₂O, and iodine have been investigated. They reveal the participation of an RCo(DH)₂H₂O · I₂ intermediate which undergoes intramolecular transalkylation and acts as an electrophile towards a second organocobaloxime molecule. The trend in reactivity as the R group is varied is discussed.     

Chemistry of metal hydrides : XXI. Insertion of acetylenes into palladium hydrides

trans-Pd(NO₃)H(PCy₃)₂ (I) when treated with Et₄NCl forms the hydride trans-PdClH(PCy₃)₂ which in turn reacts with AgPF₆ in acetonitrile to give trans-[PdH(CH₃CN)(PCy₃)₂]PF₆ (III). Both I and III react smoothly with acetylenes containing one electron-withdrawing group to give alkenyl products. The geometry of the resulting alkenyl ligand implies that cis addition has occurred and that the hydridic hydrogen adds to the acetylenic carbon containing the electron-withdrawing group.Acetylenes containing two electron-withdrawing groups give mixtures from which both alkenyl and zerovalent acetylene compounds can sometimes be isolated. In the presence of proton sponge, monosubstituted acetylenes still give alkenyl products while those substituted with two electron-withdrawing groups give the zerovalent products in good yield. The relevance of these results to an understanding of the nature of the migratory insertion reaction is discussed.     

Titrimetric determination of vanadium(IV) with DCTA

Vanadium(IV) has been determined by DCTA titration conductometrically, spectrophotometrically and visually (with Alizarin Red S, Gallein and Catechol Violet as indicators at pH 4.0, 4.2 and 4.5-4.6 respectively). The interference of nickel, copper, lead, aluminium and thorium can be removed, and the method utilized for the analysis of binary mixtures of vanadium(IV) with nickel, copper or thorium.     

Defect aggregation in anion-excess fluorites II. Clusters containing more than two impurity atoms

A theoretical study has been made of defect clustering in fluorite crystals. The emphasis is on the aggregation processes that can occur beyond the dimer stage which was discussed previously (J. Corish, C. R. A. Catlow, P. W. M. Jacobs, and S. H. Ong,Phys. Rev. B25, 6425 (1982)). The systems studied comprise CaF₂, SrF₂, and BaF₂ doped withMF₃whereM =Y, Lu, Yb, Er, Tb, Gd, Eu, or La, and also SrCl₂ doped with GdCl₃, LaCl₃, or PrCl₃. Two tetramers, one containing a single anion vacancy and two 〈111〉 relaxed F^? ions and the other with a planar arrangement of the dopant ions, are stable for certain systems while a trimer and hexamers, with an octahedral arrangement of substitutionalM³⁺, also show considerable stability. A notable feature is the increase in the relative stability of larger complexes as the ratio of the radius of the dopant ion to that of the host lattice cation is decreased. The results are discussed in relation to recent EXAFS and neutron scattering work on these systems and should provide a useful guide in future experimental studies.     

Thermal degradation of polyether-urethanes: 5. Polyether-urethanes prepared from methylene bis(4-phenylisocyanate) and high molecular weight poly(ethylene glycols) and the effect of ammonium polyphosphate

Polyurethanes prepared by reaction of methylene bis(4-phenylisocyanate) with poly(ethylene glycols) with molecular weights of approximately 1000 and 1500 have been degraded thermally, alone and in the presence of ammonium polyphosphate (APP). Degradation has been carried out at temperatures up to 500°C and the volatile products and structural changes in the residue analysed in detail. From these data, comprehensive mechanisms have been deduced and discussed and the differences in absence and presence of APP emphasised.A brief general discussion of this and previous work on polyetherurethanes (PEU) is presented, which illustrates in particular the effect of the length of the polyether segment on the degradation reaction.     

Olefin complexes of rhodium(I) containing the ligands but-3-enyldiphenylphosphine and diphenylpent-4-enylphosphine

But-3-enyldiphenylphosphine (mbp) and diphenylpent-4-enylphosphine (mpp) react with Rh₂Cl₂(C₂H₄)₄ (molar ratio $\text{2}\text{1}$ to form the four coordinate dimeric complexes Rh₂Cl₂(mbp)₂ and Rh₂Cl₂(mpp)₂ respectively, while but-3-enyldiphenylphosphine reacts with Rh₂Cl₂(C₂H₄)₄ (molar ratio $\text{4}\text{1}$) to form RhCl(mbp)₂, a five coordinate complex in the solid state. The dimers further react with sodium tetraphenylborate to give the π-bonded tetraphenylborate complexes Rh[mbp][C₆H₅)₄B] and Rh[i-mpp][(C₆H₅)₄B] where i-mpp = (C₆H₅)₂P(CH₂CH₂CHCHCH₃). RhCl(CO)(mbp)₂ reacts with sodium tetraphenylborate to form the five coordinate cationic complex [Rh(CO)(mbp)₂][(C₆H₅)₄B]. Both RhCl(CO)(mbp)₂ and RhCl(mbp)₂ react with hydrogen in methanol saturating the olefin to form RhCl[CO][(C₆H₅)₂P(C₄H₉)]₂ and Rh₂Cl₂[(C₆H₅)₂P(C₄H₉)]₂ respectively.     

The structure of the proton skeleton in 1,3-butadieneiron Tricarbonyl as determined from the NMR spectra of oriented molecules

¹H NMR spectra of 1,3-butadieneiron tricarbonyl oriented in a nematic liquid crystal solvent have been analysed and used to derive the structure of the proton skeleton, which is found to be non-planar. The distance of the anti protons from the plane defined by the remaining four protons is 0.77 ± 0.06 ±.     

Synthesis and properties of some 2-(dimethylamino)methyl-substituted arylcopper compounds

The synthesis and isolation of 2-[(dimethylamino)methyl]phenylcopper and its 5-methyl, 5-methoxy, 5-chloro and 3-chloro derivatives are described. These hydrocarbon-soluble arylcopper compounds are appreciably more thermally stable than phenylcopper (e.g. 2-[(dimethylamino)methyl]phenylcopper decomposes only at 175–185°). They also show improved hydrolytic and oxidative stability.Lithiation of 1-methoxy-4-[(dimethylamino)methyl]naphthalene with butyllithium occurs at the 5-position. Metathesis of 1-methoxy-4-[(dimethylamino)methyl]-5-lithionaphthalene with cuprous bromide affords the corresponding organocopper compound.     

Copper(II)-cetyltrimethylammonium chloride-chromal blue G ternary complex and its application to the spectrophotometric determination of copper(II)

A sensitive spectrophotometric method for the determination of copper(II) based on a ternary complex with chromal blue G, a triphenylmethane reagent in the presence of cetyltrimethylammonium chloride, is described. The sensitivity of color reaction between copper and chromal blue G has been greatly increased by the sensitizing action of cetyltrimethylammonium chloride, a cationic surfactant. The color development of the ternary complex can be utilized in the highly sensitive spectrophotometric determination of copper. The molar absorptivity of the binary complex between copper and chromal blue G ε_630nm = 9.56 × 10³liters · mol⁻¹ · cm⁻¹ is enchanced on ternary complex formation to ε_{542 nm} = 4.78 × 10⁴liters · mol⁻¹ · cm⁻¹. The ternary complex gave a maximal absorbance at 542 nm in the pH range 9.8–11. Beer's law is obeyed up to at least 1.2 ppm of copper. The maximal absorbance of the ternary complex was found to develop within 5 min and then it remains constant for several hours. The formation constant of the ternary complex is calculated to be 8.6 × 10¹⁰ under these conditions.     

The formation of lithium diarylargentates from arylsilver compounds and the corresponding aryllithium compounds

Diarylsilverlithium compounds of the type Ar₂AgLi are formed by treating arylsilver compounds with the corresponding aryllithium compounds. Cryoscopy in benzene shows that the Ar₂AgLi compounds are associated into dimers. NMR spectroscopic data indicate that only one type of aryl group is present in these dimers, and that each aryl group is bridging between one silver and one lithium atom.     

Kinetische und mechanistische untersuchungen von Übergangsmetall-komplex-reaktionen : III. Abhängigkeit des gleichgewichts der addition von tributylphosphan an pentacarbonyl(arylmethoxycarben)wolfram vom substituenten am ring

The reaction of pentacarbonyl(arylmethoxycarbene)tungsten, (CO)₅W[C(OCH₃(p-C₆H₄R)] [R = OCH₃ (a), CH₃ (b), H (c), Br (d), CF₃ (e)], with tributylphosphane at low temperatures results in a reversible addition of the phosphane to the carbene carbon atom. The addition—dissoziation equilibrium is not only dependent on the temperature but also to a strong degree on the nature of the substituent R. ΔG, ΔH and the equilibrium constant K increase in the series from R = OCH₃ to R = CF₃. With the exception of R = OCH₃ the substituents b to e form an isentropic class. For all substituents (a to e) a linear dependency from Jaffés σ-constants was observed for ΔH. Good linear correlation for the substituents b to e was also found for log K and σ as well as for log K and the CO-force constants k_cis and k_trans.     

Resonance Raman spectra of 15N enriched metallooctaethylorphyrins. Characterization of the oxidation state marker bands of hemoproteins

Resonance Raman spectra of ¹⁵N enriched metallooctaethylporphyrins [M(OEP) ? ¹⁵N₄] [M = Ni²⁺, Fe³⁺ (high spin), and Fe³⁺ (low spin)] were observed. Polarized Raman lines corresponding to the oxidation state marker band of hemoproteins were observed at 1377 (Ni), 1369 (Fe high spin) and 1372^?1 (Fe low spin) which were shifted to lower frequency from those of the ¹⁴N compounds by 6, 5, and 6 cm^?1, respectively. The vibrational mode for this band was shown to include an appreciable contribution of the C_αN symmetric stretching vibration and to be associated with ca. 0.01 Å of in-phase displacement of the four pyrrole nitrogens toward the metal ion.     

Organostibines as ligands. Synthesis of dimethyl(α-picolyl)stibine,dimethyl(8-quinolyl)stibine,and (R;S)-methylphenyl(8-quinolyl)stibine and some transition metal derivatives

The unsymmetrical mono-tertiary stibines dimethyl(α-picolyl)stibine (picstib), dimethyl(8-quinolyl)stibine (quinstib), and (R;S)-methylphenyl(8-quinolyl)stibine (R;S-quinstib) have been synthesised and the square-planar complexes [MX₂(picstib)], [MX₂(quinstib)] (where M = Pd or Pt and X = Cl, Br, I or SCN) and [MCl₂(R;S-quinstib)] (where M = Pd or Pt) isolated. The thiocyanato derivatives display linkage isomerism. The octahedral complexes [M(CO)_4-(picstib)] and [M(CO)₄(quinstib)] have also been prepared from the metal hexacarbonyls and the appropriate ligands by UV irradiation in tetrahydrofuran.     

Direct ortho-mercuration reactions of azobenzene and ortho-substituted azobenzenes

The mercuration of azobenzene occurred exclusively in the ortho-position to yield 2-chloromercuriazobenzene and a mixture which on iodination gave 2,2'and 2,6-diiodoazobenzene. Ten other ortho-substituted azobenzenes were mercurated and mercuration was found to occur predominately in an ortho-position. The regiospecificity of these reactions suggests that the mercury is directed into an ortho-position by coordination of the mercury to an azo nitrogen and then subsequent electrophilic substitution.     

Schiff base complexes of organotin(IV): Reactions of trimethyltin hydroxide and trialkyltin ethoxides with benzothiazolines

Twenty-three new volatile trialkyltin derivatives of sulphur containing Schiff bases have been synthesized by the reactions of trimethyltin hydroxide and trialkyltin ethoxides with 2,2-disubstituted benzothiazolines. On the basis of molecular weight measurements and infrared proton magnetic resonance spectra, five coordination at tin is proposed for these complexes.     

Synthese eines verbrückten π-allyl-chinolin-palladiumchlorid-komplexes

Chloro[N-3′5′-η-(4′-methylpentenyl)quinoline-2]palladium was synthesized; the NMR-spectrum of this compound is helpful in distinguishing the cis/trans-isomers of other non-bridged π-allyl-base-palladium chloride complexes.     

NMR study of hydrogen molybdenum bronzes: H1.71MoO3 and H0.36MoO3

Proton NMR relaxation times (T₂T₁, and T_1?) and absorption spectra are reported for the compounds H_1.71MoO₃ (red monoclinic) and H_0.36MoO₃ (blue orthorhombic) in the temperature range 77 K < T < 450 K. Rigid lattice dipolar spectra show that both compounds contain proton pairs, as OH₂ groups coordinated to Mo atoms in H_1.71MoO₃ and as pairs of OH groups in H_0.36MoO₃. The room temperature lineshape for H_1.71MoO₃ shows that the average chemical shielding tensor has a total anisotropy of 20.1 ppm. The relaxation measurements confirm that hydrogen diffusion occurs and give E_A = 22 kJ mole^?1 and $\text{τ}{}^0{}_{\mathrm{<mtext>C</mtext>}}\text{? 10}{}^{\mathrm{?13}}\text{sec}$ for H_1.71MoO₃ and E_A = 11 kJ mole^?1 and $\text{τ}{}^0{}_{\mathrm{<mtext>C</mtext>}}\text{? 3 × 10}{}^{\mathrm{?8}}\text{sec}$ for H_0.36MoO₃.